I have heard that NASA is looking for a new planet like the earth, is this possible??
Actually, NASA is certainly not the only organization looking for such planets, so perhaps the question should be slightly reworded to whether astronomers in general are likely to find such planets.
The answer is that it depends on what you mean by “a planet like the earth.” If you are asking whether there is likely to be a rocky planet of approximately the right size at approximately the correct distance from a star of approximately the right size and temperature to support life, The answer is that almost certainly there will be earth-like planets by that definition. In fact, there are probably many billions of planets which are like the earth in that way. With the already existing technologies or with relatively minor improvements, such planets will probably be discovered in our lifetimes.
A better question is whether there will be planets with the right elemental composition, of the right size, at the right distance from a star with the right temperature which also has:
sufficient organic matter
a large enough moon to create a stable orbit so that life can evolve long-term as it has on the earth
other absolutely necessary parameters that I am not aware of or which scientists today are not aware of.
If you are asking about a planet with all the components necessary to the creation of life and to evolution to the point of having highly evolved, complex life forms, then my answer is that I am not sure, as it is difficult to make this much more complex calculation. Besides, judging whether a planet which fits the full profile of properties capable of supporting an evolving complex ecology involves questions which will not be answerable by the current methods of locating planets outside our solar system.
The new discoveries of a great variety of planets outside our solar system is really exciting science. I follow this with eagerness. I am not in the least surprised that such planets exist, but their discovery is really awesome. However, whether there are earth-like planets with all the requisite components for advanced life forms to exist will probably remain an open question for a long time and our ability to make the calculation of the probability of such a planet existing is not sufficient to make a good evaluation.
I say that it just might be possible that such planets exist, but we simply do not know at this point. I hope this helps.